Electron discharge device



1937- G. PASSARGE ELECTRON DISCHARGE DEVICE Filed Dec. 5, 1936 INVENTOR GERHARD PASSARGE BY gad/umw ATTORNEY Patented Nov. 16, 193-7 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE tion of v Application December 5, 1936, Serial No. 114,385 In Germany November 15, 1935 ZClaim.

This invention is directed to the construction of discharge tubes for the generation, amplification and rectification of alternating currents.

The use of ceramic materials such as porcelain in the construction of envelopes for discharge tubes is known. It is also known in the prior art to make the anodes by depositing a metallic layer on the side of a ceramic envelope facing the cathode.

High frequency oscillatory systems, containing condensers and inductances are easily disturbed in their resonance i'requency with changes of temperature of the parts of the system. It is difllcult to operate a tube at optimum frequency if change 01' temperature influences interelectrode spacing and capacities. This difllculty is minimized according to this invention by so constructing the tube parts that little changes of electrode shapes and spacings are caused by temperature 29 changes.

According to this invention all electrodes are made of ceramic material coated with metallic layers. It is proposed to solidly support upon ceramic material all metal parts within the envelope.

The characteristic features of this invention are illustrated in the drawing which shows by way of example one form of tube. The cathode of the discharge tube is represented by a tubular ceramicbody 0 whose exterior surface is coated with a metallic layer b. That part of the cathode extending into the discharge space supports an active emission layer c which may consist for example of thorium or alkaline earth oxide. In

35 side hollow body a is disposed heating element d to heat the cathode to the emission temperature of active layer 0. Hollow body a may remain open so that heating element (1 may be exchanged without diiiiculty, or it may be closed and filled with an inert gas. Surrounding the cathode is a cylindrical grid electrode consisting of a molded ceramicbodye. Bodyeiscloudattheupper endandisperi'oratedinthedischargespace opposite the cathode. The surface of the ceramic body is provided inside and/or outside with a metallic coating I. The envelope of the device comprises a ceramic cylinder )1 lnteriorly and exteriorly plotted with metallic coating i, k to form an anode.

The cathode grid and anode above described may conveniently be assembled by tapering the electrodes at their endsand iitting them together with tapered insulating rings 1 and m. The taperedsuriacesoftheringsandtheelectrodesmay llbeiclnedgas-tisbt stmingthssuriacuwitb intermediate layers of glass or solder with flux. The surfaces to be connected are coated with a solder and are pressed together when heated to the melting temperature of the solder. For degassing this novel tube, an exhaust tube may be 5 connected to one of pieces I, m, or to one of the electrodes.

External connections of the electrodes to. the

- various circuit elements is accomplished in a most simple manner in the embodiment shown, 10 since all metallic layers serving as electrodes extend through the envelope and are easily accessible without the usual lead-in wires. The connections may be made for instance by clamps placed around the elements in question. It is 15 evidently not necessary to metallize the whole outer side of the individual ceramic supporting bodies but it is desirable to extend the metallizing in the form of a band to that place where the connections are to be made with the exterior a0 circuits. Suitable contact elements may be embedded in the ceramic materials.

Tubes constructed according to this invention may be made by machines with very small tolerances. The various ceramic bodies may belt pressed and sealed together in a very simple manner and the metal coatings may be easily and uniformly applied. Ground tapered joints permit accurate spacing oi the electrodes. An advantage of ceramic materials for tube parts so lies in their small temperature expansion ooei' ilcient, which results in small deformations oi the tube parts during use with the consequential stability of the tuning of connected oscillating systems. Different parts of the tube may be made 86 of ceramic material of different composition, whose temperature expansion coemcients are different so that a complete compensation for heat distortions may be eiiected.

I claim: 40

In an electron discharge device. an indirectly heated cathode comprising a metal coated sleeve 01' insulating material, a grid electrode comprising a metal coated cup-shaped ceramic manbcr oflargerdiameterthanandconcentricwith said cathode and perforated opposite said cathode, andananode comprisingametal coatedceramic cylinder, and a ceramic ring ior insulatingly sealingsaid cathode tube intermediate its ends 0 inoneendoi'saidcylinderandasecondceramic m for insulatingly sealing aa-fls aid a electrodeintermediateitsendsintheotherend oi said cylinder.

GERARD PABSARGI. lo 

